Propeller pitch and diameter control



July 16, 194

I F. DU P. AMMEN PROPELLER PITCH AND DIAMETER CONTROL 2 Sheets-Sheet 1 I Filed Oct. 6, 1941 INVENTOR Patented July 16, 1946 PROPELLER PITCH AND DIAMETER CONTROL Francis Du Pont Ammen, Los Angeles, Calif.

Application Gctobcr 6, 1941, Serial No. 413,741

4 Claims. (Cl. 170-160) This invention relates to aircraft propellers, and the general object of the invention is to pro-- vide means for controlling at will, the pitch or diameter of the propeller, for the purpose of improving the maneuvering capabilities of such craft. This quality is most advantageous in combat aircraft or fighters that accompany bombers in their flights, for protecting the same against attack by the enemys intercepter craft.

The invention is particularly applicable to aircraft in which the propeller shaft is driven by two or more motors, and in which the pitch is normally automatically controlled by running conditions of the engines or motors of the power plant.

One of the objects of the invention is to pro vide control mechanism through the agency of which the pitch or the diameter of the aircraft may be changed at will, by an operator on the craft, and to accomplish this by temporarily discontinuing the normal automatic pitch control of the propeller blades.

A further object of the invention is to provide means for changing the diameter of the propeller at will, and for changing the pitch if desired, without necessitating the employment of any pressure-controlled devices such as hydraulic cylinders or electro-magnetic means located at the propeller hub; also to accomplish this in a fighter type of aircraft employing a hollow or tubular propeller shaft through which a gun can be fired.

In the preferred embodiment of the invention, means are employed extending along the propeller shaft for changing the pitch of the blades, and, or, extending the same to alter the diameter of the propeller. And one of the objects is to provide a construction including a continuously driven control mechanism, in which slight shifting movements of a relatively fixed part will effect desired changes in the pitch or diameter of the propeller.

A further object of the invention is to provide means associated with the control mechanism for indicating the pitch, and also the degree to which the blades are extended; also to provide automatic means for preventing the blades from being extended beyond a predetermined diameter.

Further objects of the invention will appear hereinafter.

The invention consists in the novel parts and combination of parts to be described hereinafter, all of which contribute to produce an efficient propeller pitch and diameter control.

' A preferred embodiment ofthe invention is described in the following specification, while the broad scope of the invention is pointed out in the appended claims.

In the drawings:

Fig. 1 is a horizontal section through the propeller hub and shaft, the latter being shown partially in elevation. This view also shows the propeller control mechanism at the rear of the propeller shaft, and also indicates the drive from the motors to the propeller shaft.

Fig. 2 is a vertical section taken about on the line 2--2 of Fig. 1.

Fig. 3 is a vertical section taken about on the line 3-3 of Fig. 1, further illustrating the control mechanism at the rear of the propeller shaft, and further illustrating the gears and the means for indicating the pitch existing at the moment, and also the degree of extension of the propeller lades, that is, the present propeller diameter.

Fig. 4 is a. vertical section taken about on the line 4-4 of Fig. 2, and particularly illustrating the automatic and the at will drives for the pitch-control with the clutch means for using either of the same.

Fig. 5 is a diagrammatic view illustrating means for arresting the outward movement of the blades at the limit of their outward movement.

Fig. 6 is a fragmentary view further illustrating the control lever and means carried by this lever for automatically giving the desired direction of adjusting orientation to a planetary ring to change the pitch in the desired direction.

In the drawings, I indicates the propeller shaft which is of tubular form, the rear end of which carries a propeller hub 2 splined on the same at 3. This hub carries one or more pairs of diametrical opposite propeller blades 4, each blade having a shank 5 mounted in the hub for radial shifting movement in and out. In order to accomplish this and at the same time to provide for altering the pitch of the blades, each shank is connected by a spline connection 6 to a sleeve 1 that is mounted for slight rotation on its own axis in a socket 8 in the propeller hub. Each sleeve 1 is rigid with a bevel gear 9 meshing with a bevel gear I U splined on an inner shaft II. This is the pitch control shaft, the rotation of which relative to the propeller shaft I, will of course rotate the sleeves and thereby rotate the blades on their axes to change their pitch.

Each blade shank 5 is formed with a thick web l2 threaded as a nut on a radial adjusting screw l3, the inner end of which is mounted in a hearing [4 in the hub ofgear 9; and the adjusting screw [3 is formed at its inner end into a bevel gear i5 meshing with a bevel pinion l6 splined on intermediate inner shaft ll. This is the diameter control shaft, the rotation of which relative to the propeller shaft, will rotate the adjusting screws and adjust the blades in or out.

Follower rings l8 threaded into the outer ends of the sockets 8, hold the sleeves l in the sockets.

The propeiler shaft is rotatably mounted in a bearing it in the nose of the nacelle or the nose of the fuselage.

In the present drawings, the propeller shaft l is supposed to be located between two motors, each motor driving a gear wheel 29. These gears 29 mesh with opposite sides of a gear wheel 2| keyed or splined on the propeller shaft.

At the inner end of the propeller shaft I provide a planetary gear mechanism through which the pitch shaft l l and the diameter control shaft may be controlled by automatic controls, and this mechanism is so constructed that when desired, the automatic controls can be inhibited and the pitch and diameter of the propeller controlled at will through hand-controlled power-driven mechanism. This mechanism is preferably driven off the propeller shaft, and will now be described.

The inner end of the propeller shaft l carries a rigid sun gear 22 that meshes with, and drives a planet gear 23 rolling around inside a fixed internal gear 2d, and the shaft 25 of this gear is carried in a planetary ring 26 that rotates on the axis of the propeller shaft. This planetary ring 23 carries the shaft 2'! of a second planet gear 23 that meshes and rolls at its outer edge on a relatively fixed internal gear 29, and meshes at its inner edge with a gear wheel 30 rigidly attached on the inner end of the diameter-control shaft ll. The gear 28 is the same diameter as gear 23, and gear 35 is the same diameter as gear 22. Hence, as the planetary ring 26 rotates, the gear 28 will drive the gear 3% and the control shaft H at the same speed as the propeller shaft. Under these circumstances, the distance of the blades 4 from the propeller axis remains fixed, that is, they maintain a fixed diameter for the propeller.

Through similar planetary mechanism the pitch control shaft ii is driven normally at the same speed as the propeller shaft, thereby maintaining the pitch normally constant. This mechanism includes a gear wheel 3! mounted on a shaft 32' on the planetary ring 26, and meshing and rolling at its outer edge on a, relatively fixed internal gear 32; and meshing at its inner edge with a driven gear 33 rigid on the pitch shaft H. The gear 3| is of course of the same diameter as the gear 23; and the gear is the same diameter as the gear Also the three internal gears 24, 2%, and 32 are of the same diameter. Evidently by orienting the relatively fixed gears 29 and 32 forward or back on the axis of the propeller shaft relative rotation of the shafts ll or i i with respect to the propeller shaft i can be effected, and this will accomplish the desired adjustments of the propeller blades, for pitch and diameter. relatively fixed gears 25 and 32 is a positive and absolute rotation. These two relatively fixed internal gears are provided with means enabling the same to be normally controlled constantly by automatic controls of the aircraft, but this means is so constructed that at any instant the automatic contro1 may be discontinued and control at will substituted.

The pitch control gear or ring 32 has worm teeth E l on its exterior (see Fig, 2) meshing with a worm 35 carried on a counter shaft 35a. This worm is normally controlled from an automatic This orientation of the control shaft 36 and bevel gears 31 and 38, the latter of which is normally clutched in through the clutch members 39 and it to drive the worm shaft. In practice, the automatic control shaft 36 would be connected to any of the well known automatic pitch control elements, for example, the hydraulic pressure controlled device shown in Patent No. 2,232,683, granted February 25, 1%941, to C. l/V. Lloyd. The clutch member 39 is illustrated as integral with the sleeve or hub of the bevel gear 38. When these clutch members are in engagement, any rotation of the automatic control shaft 3% of the aircraft will impart slight but positive and absolute adjusting movements to the propeller blades to alter their pitch. 7

But if the clutch member 40 which is splined on the countershaft 35a, is moved down from its neutral position, to engage clutch member 4! which is rigid with bevel gear 42, then motion can be transmitted to the worm from a slowly rotating shaft G3 that is continuously driven through a reduction gear mechanism 44 which reduction gear mechanism is driven continuous- 1y by gears 45 and 46 from the propeller shaft I. The reduction gear M drives two bevel gears 41 and 48 slowly in opposite directions. A clutch member consisting of a double bevel gear 49, is splined for shifting movement along shaft 43. This clutch gear 49 is normally in an intermediate neutral position as shown in Fig. 1, and is shifted to the proper bevel gear 41 or 48 through the operation of either of two solenoids 50 and 5!, the cores of which connect to the clutch lever 52 that is yoked at its lower end to the hub of the double bevel gear 49. An electric circuit illustrated diagrammatically by wires 53 is closed through either of these solenoids by an auxiliary switch lever 54 (see Figs. 4 and 6) that is pivotally mounted on the clutch lever 55 that shifts clutch member 40 already described. Insulated contacts 56 on this auxiliary lever may engage either contacts 51 or 58. This operates the electrically controlled clutch lever at 52 in the proper direction to give the desired direction of rotation to the control shaft 43. After selecting the desired direction of drive, the lever 55 is then swung down to interclock clutch members 40 and 4!. The pitch of the propeller blades will then gradually change in the desired direction. A pitch indicator scale 59 (see Figs. 2 and 3) may be provided in the form of a thin plate or segment cooperating with a fixed zero point 60 (see Fig. 2) on a fixed shield or plate 6| The mechanism for controlling the propeller diameter by rotating the relatively fixed gear or ring 2!! forward or back, is illustrated as composed of similar elements and organization of parts as in the pitch control mechanism just described. This would include a reduction gear mechanism 62 driven from gear 45 through gear 63, driving two bevel gears 64 and 65 at slow speed in opposite directions. Cooperating with these bevel gears is a double bevel gear 66 normally in the neutral position shown in Fig. 1, but capable of being shifted by a clutch lever Ii! that in turn is controlled by two solenoids 68 connected into a circuit 69 corresponding to, and having the same wiring as, circuit 53. An upper shaft 10 like the shaft 36, is provided, that would be connected to automatic mechanism of the aircraft, for controlling the propeller blades radial adjustment for adjusting the propeller diameter. There is also a lower shaft H corresponding to. shaft 43. Through bevel gears '12 and 73, either of these shafts can drive a worm shaft 14 through clutch-member '15, said shaft 14- carrying a worm 16 that meshes with the wormteeth 29a on the relatively fixed gear 29, the rotation of which will drive the diameter shaft ll through planet gear 28 and gear 30.

A clutch lever 11 is provided similar to lever 55, that normally holds a clutch member 18 up against clutch member 79 if it is desired to maintain automatic diameter control. But when clutch member 18 is moved into engagement with clutch member 19a, then the worm 16 will be driven. To determine the driving direction, the lever ET is provided with a direction-control switch 80 actuated by a handle 8| pivoted on lever'i? constructed like lever handle 54. These levers 55 and '51 are mounted as illustrated in Fig. 4, so as to cooperate with a locking quadrant 82 with notches 83. Each lever would have a bolt 84 to lock the same in any one of the notches,

Although I have illustrated the mechanism as provided with only one planet gear 23, it should be understood that in a practical design, in order to give better balance and efficient operation, it would be preferable to employ three such gears spaced 120 apart. This would also be advisable as regards planet gears 28 and 3|.

As the planet gear 3| is located considerably out of the plane of the planet ring 26, this ring is provided with an integral oflset bracket 85 to give a good support for the pin or stubshaft 32 of planet gear 3|.

The relatively fixed gear ring 29 for the diam eter control is provided with a scale 86 (see Fig. 3) to cooperate with the fixed index point 60, and this scale when in its neutral position (when the blades are half way extended) would be colored on the right with a color to contrast with the color on the left. In this way the scale will indicate whether the blades have been moved in or out off of neutral, as well as indicating the amount they have been moved. Although this scale 86 is illustrated connected directly to the gear ring 29, in practice reduction gearing (not illustrated), should be employed for driving this scale because the ring 29 would have to make more than one complete revolution in imparting the maximum in or out shift of the propeller blades.

In practice, a stop ring (not illustrated) should be provided on the outer end of each blade socket to cooperate with an annular shoulder on theblade shank, but I prefer to employ with such a construction (for fear that the propeller shank might jam against it), an electrically controlled clutch 8"! on shaft H (see Fig. 1). At the limit of outward movement of the blade shank an insulated contact 38 upon it (see Fig. will engage an insulated contact 89 and close a circuit 90 through a solenoid 9!. This solenoid pulls open the clutch 8'! and stops the drive to the blade. The drive to the blade screw I3 should then. be reversed by operating lever 11 and its handle switch 8i. As this is done, the clutch 81 should be reclosed by hand, with a hand-lever (not illustrated).

The mode of operation of the entire mechanism will now be briefly stated:

Automatic pitch control from shaft 36 is normally maintained through clutch 39, 40 which is normally closed. Any adjusting rotation of worm 35 through this medium, will cause an adjusting orientation of ring 32, thereby imparting relative movement of inner shaft H forward or back with respect to the propeller shaft I. This will impart the adjusting movement through the bevel gears l0 and 9 to the blade'sleeves 1.

This will rotate the blades 4 on their longitudinal axes and change their pitch.

When it is desired to inhibit the automatic pitch control and change the pitch at will, the

clutch member 40 is moved against clutch mem ber 4| by operating lever 55. This lever is moved by means of its handle 54 that closes. a circuit through either of the solenoids 59 or 5| to determine the direction of movement, to increase or decrease the pitch. For one direction the drive wouldbe from bevel'gear 47, and for the other, from gear 48.

The change of propeller diameter is efiected through mechanism similar to that just referred to, by moving the lever 10 to close clutch member '15 against clutch member 19. The direction of drive is controlled by the switch handle 8i (see Fig. 1) cooperating with its two contacts to close the circuit through either one of the solenoids 68 and 69. to shift the double bevel gear 66 into contact with either one of the driving bevel gears 64 or 65. This of course will drive worm 76 in the proper direction to rotate the gear ring 29 forward or backward with respect to the direction of rotation of the propeller shaft, and this will operate through planet gear 28 to rotate gear 30 and the diameter control shaft IT, to rotate the screws I 3 in the proper direction to move the blades out Or in. This drive should be slow enough to prevent any possibility of its getting out of control of the operator.

In effecting a pitch adjustment or a diameter adjustment the amount of the adjustment is always in positive control and its amount is pro- In this specification the pitch control and the propeller diameter control have been described as independent of each other for the reason that this would give a maximum effect in maneuverability of the aircraft, which is highly desirable in military aircraft. It is obvious, however, that if desired, features of this invention can be employed with a propeller blade mounting in which the pitch of the blade would change automatically as the shank of the blade moves in or out. This would be accomplished by giving pitch to the splines 6 in a manner already old in this art. This arrangement might be desirable in aircraft designed for commercial use, and would enable the propeller diameter and pitch both to be increased for stratosphere flying. The relatively small diameter would facilitate landing and would incidentally enable ground clearances to be reduced, with the fuselage lying nearer to the ground level forward.

The bearing I9 is illustrated merely as a, conventional bearing. In practice, a proper thrust bearing would be located in this general location to take the enormous thrust forces that would be developed in flying.

Many other embodiments of the invention may be resorted to without departing from the spirit of the invention.

What I claim is:

1. In a propeller apparatus for aircraft, the combination of a propeller shaft, a propeller hub carried thereby, propeller mounted on the hub, a planetary gear mechanism, with means driven through the same for changing the position of the said blades, a control shaft for the planetary mechanism, driving mechanism for the control shaft, an electrically controlled device for enabling the driving mechanism to rotate the control shaft in either direction, a hand-operated member and a clutch operated by the hand-operated member for connecting up the control shaft to the planetary mechanism, and a switch lever carried by said hand-operated member, with means associated with the switch lever for closing a circut through said electrically controlled device for determining the direction in which the control shaft will be driven.

2. In propeller apparatus for aircraft, the combination of a propeller shaft, a propeller hub carried thereby, propeller blades movably I mounted on the hub for regulating their pitch and extensible radially from the hub, a planetary gear mechanism adjacent the inner, end of the shaft, said planetary gear mechanism including a relatively fixed pitch-control gear and a relatively fixed diameter-control gear, orienting means for adjustably orienting the pitch-control gear forward or back, means actuated by the said orientation at the said planetary gear mechanism for moving the blades to alter their pitch, means for adjustably orienting the said diametercontrol gear forward or back, and means connecting the planetary gear mechanism to the blades for extending the same through the medium of said orientation of the said diametercontrol gear.

3. In propeller apparatus for aircraft, the combination of a propeller shaft, a propeller hub carried thereby, propeller blades movably mounted on the hub for regulating their pitch and extensible radially from the hub, a planetary gear mechanism adjacent the inner end of the shaft, said planetary gear mechanism includin a relatively fixed pitch-control gear and a relatively fixed diameter-control gear, orienting means for adjustably orienting the pitch-conblades movably trol gear forward or back, means actuated I through the planetary gear ,mechanism by the said orientation, for moving the blades to alter their pitch, orienting means for adjustably orienting the said diameter-control gear forward or back, means connecting the planetary gear mechanism to the blades for extending the same through the medium of the said orientation of the diameter control gear, the said orientin means being respectively located on opposite sides of the propeller shaft; and a lever and clutch corresponding to each of the orienting means for connecting the same for actuation.

4. In a propeller apparatus for aircraft, the combination of a propeller shaft, a hub carried by said propeller shaft, blades mounted on the hub with adjusting means for radially adjusting the'blades in the hub, a planetary gear mechanism including a control gear having teeth for meshing with the planetary gear wheels of the mechanism and having worm teeth, a worm meshing with said worm teeth for orienting the control gear forward and back, means connected to said adjusting means and controlled by the control gear for radially adjusting the blades in the hub, a shaft adapted to be automatically controlled normally connected with the worm for automatically controlling the adjusting movements imparted to the blades, means for efiecting the substitution of control means positively controlled at will of the operator for rotating the said worm in either direction to radially adjust the blades in the hub, a scale for indicating at all times the degree of extension of the blades, means for mounting said blades so as to be rotatable about the blade axes to adjust the pitch of said blades, said planetary gear mechanism including a second control gear for cooperating with the panetary gears of the mechanism to effect adjustments of the pitch of the blades, and having worm teeth, a pitch worm meshing with the worm teeth of said second control gear; and a shaft adapted to be driven by an automatically controlled shaft for actuating the pitch worm automatically.

FRANCIS DU FONT AMMEN. 

